The NIDDK initiated a nationwide study designed to determine whether it is possible to prevent or delay IDDM. The initial plan is to screen for ICAs in first (& second) degree relatives of people with IDDM. Individuals who screen positive are invited to undergo additional testing. Based on these results, randomization to a control vs intervention group (with insulin treatment) will be offered. This protocol is for initial ICA screening only. Additional protocol(s) will be submitted in the near future.